Journal of Structural Engineering

This paper analyzes the wind pressures on the claddings of a 600-m-high skyscraper in Shenzhen, China, during Super Typhoon Mangkhut on September 16, 2018. A synchronous monitoring system that included 48 pressure transducers was implemented to measure the cladding pressures of the skyscraper during the typhoon event. Based on field measurements, the mean, root-mean-square fluctuating, peak (maximum and minimum) pressure coefficients are presented and discussed. Then the mean and peak pressure coefficients are used to validate the design values stipulated in the design code of China. Comparative study finds that the design values of the peak pressure coefficients on the windward and leeward faces of the skyscraper are conservative, while those on the side faces are nonconservative. As for the mean pressure coefficients, the design values are conservative for all faces. Moreover, the non-Gaussian characteristics, power spectral densities, coherences, and correlations of the measured cladding pressures are analyzed to explore the mechanisms of pressure fluctuations on the four sides of the skyscraper. This paper aims to enhance understanding of cladding pressures of high-rise buildings under extreme wind conditions and, therefore, to provide useful information for future designs of wind-resistant skyscrapers in tropical cyclone–prone regions.

Because of the vulnerability of roof sheathing panel to wind load, light-frame wood low-rise buildings often suffer from serious destructions in typhoon hazards. Efficient assessment of these hazards is an urgent need for the purpose of risk mitigation. The paper develops a database-assisted fragility approach for the assessment of typhoon-induced hazards to low-rise building roofing. In the developed approach, the failure of a single panel and the damage ratio of the entire roof over the typhoon duration are formulated in a probabilistic way where the dependence among wind loads is considered. Via the probabilistic formulation, the holistic analysis for typhoon-induced hazards to low-rise building roofs is decomposed to the hazard analysis at each individual time step. An analytical solution is proposed to determine the failure probability of each single panel and the probability related to the associated failure of each pair of panels at each time step. For a single panel, its failure probability is estimated by applying the Hermite transformation to the limit-state function. For the associated failure of each pair of panels, Nataf transformation is used to model the dependence between the limit-state functions of two panels. Wind field data recorded during the historical typhoon Hagupit are used to illustrate the effectiveness of the approach. Through this approach, the damage progress on roofs is revealed and the influence of wind loading dependence is investigated.

This study aimed to quantitatively develop realistic quasi-static loading protocols for simulating bidirectional cyclic actions and axial load variation on building columns in a way that is representative of an actual response during earthquake ground excitation. A case-study building was subjected to a suite of 15 ground motions that were scaled to design basis earthquake (DBE) and maximum considered earthquake (MCE) levels of a typical region of low-to-moderate seismicity. The results showed that the displacement path of a building column under earthquake actions is generally in the form of elliptical loops of various orientations due to the phase difference in the sinusoidal displacements in the two orthogonal axes of the column. Accordingly, this work proposes a bidirectional lateral loading protocol that simplifies and generalizes the displacement path of the column in the form of elliptical loops of four different orientations. Similarly, the patterns of axial load variation in columns were also studied in detail, which led to the development of separate axial load variation protocols for external and internal columns of a building, which can be applied in tandem with the bidirectional lateral loading protocol. The paper concludes with a brief overview of the results of two reinforced concrete (RC) column specimens, which were experimentally tested using the proposed bidirectional loading protocol.

A seismic damage index is validated using data from shaking table tests on full-scale and scaled reinforced concrete (RC) specimens. The experimental specimens include wall and frame lateral building systems and ductile and nonductile detailing. The index accounts for the hysteretic energy dissipated by a single degree of freedom oscillator and the building roof displacement. The use of hysteretic energy allows the index to incorporate the number and amplitude of strong-motion cycles, which are important for large-magnitude, long-duration earthquakes typical of subduction zones. Damage is found to vary linearly with normalized hysteretic energy in a way that favors wall systems over frame systems. For the same normalized displacement demand, the index predicts lower damage in wall systems. Potential applications of the damage index include: (1) measuring damage accumulation over multiple earthquakes; (2) supporting the development of risk-targeted spectra that consider the duration and amplitude of strong-motion; and (3) generating regional damage estimates after an earthquake.

Performance-based design for fire safety has been introduced in several international design frameworks. The fire models and simulations include various assumptions and simplifications, and the current fire resistance evaluation is based on deterministic approaches, leading to uncertainties in the performance of the structural members exposed to fire. An alternative is the application of probabilistic methodologies to assess the fire resistance of the structural members. The authors present the application of an efficient probabilistic methodology to perform a sensitivity analysis to identify the critical variables of a thermal model of a structural element exposed to characteristic fire loading. Furthermore, the methodology determines the reliability of the structural element. The methodology combines the elementary effects method with variance-based methods to rank the influence of the governing variables of the thermal and fire models on the thermal performance of a reinforced concrete slab and to determine their uncertainty contribution to the time-dependent thermal response. Furthermore, the Monte Carlo method is applied to calculate the probability of failure and the reliability index of the structural member exposed to fire loading. The critical governing variables from the fire model are the firefighting measures index, which accounts for firefighting measures used in the compartment ($FFMi$), characteristic fuel load density ($q_{f,k}$), compartment opening factor ($O$), and the ratio of the compartment’s floor area to total area ($A_f/A_t$). The critical governing variables from the thermal model are the coefficient of convection ($h$), concrete specific heat ($c_c$), concrete density ($d_c$), and concrete conductivity ($k_c$). As one moves away from the exposed surface, $h$, $q_{f,k}$, and $A_f/A_t$ are not as influential in the thermal response. Also observed is that the uncertainty of $FFMi$, $O$, $c_c$, and $h$ are the primary sources of the thermal response’s uncertainty. Considering the variability of the input variables, a low-reliability index is determined for buildings with no basic firefighting measures, and adding intervention measures, sprinkler systems, and detection systems will increase the reliability index by 53%, 85%, and 89%, respectively.

This study experimentally and numerically demonstrated that the traditional basic shear method is not applicable for estimating the shear stresses in tapered beams with corrugated steel webs (CSWs). The vertical components of the inclined flange forces (which are zero in the prismatic case) may decrease or increase the effective shear force on the tapered CSWs, which are reflective of the positive and negative influences of the Resal effect. In addition to the CSWs, the inclined flange also participates in resisting the shear force in a tapered beam with CSWs, and the shear forces borne by the CSWs and inclined flanges are mainly adjusted by the bending moment. Accordingly, an improved method, which is referred to as the modified shear method, was proposed in this study by considering the web shear modification of CSWs and the shear resistance of the inclined flange. The study also revealed that the effective shear force on the CSWs of regular tapered beams is actually larger than the total shear force, especially in sections that are subjected to larger moments. Thus, the calculated shear stresses in the CSWs predicted by the basic shear method are smaller than the actual values. The shear stresses that act on the corrugated webs of the reverse tapered beams with CSWs would be overestimated using the basic shear method. Parametric finite-element (FE) analysis showed that the proposed modified shear method can reflect the actual stress condition of tapered beams with CSWs. The modified shear method can be analytically reduced to the traditional basic shear method when applied to prismatic cases. This study is expected to provide a novel strategy and theoretical guideline for rapidly and efficiently obtaining the shear stresses in a variable cross-section beam with CSWs.

The classical approach for the thermal analysis of solids and fluids uses the strain additive decomposition to account for the effect of the temperature. This strain-based approach does not properly capture the effect of complex stress-free reference-configuration geometry, is applicable only to small deformation problems, and leads to simplified expression for the Green–Lagrange strain tensor. In view of the geometric description of the absolute nodal coordinate formulation (ANCF), a new ANCF gradient-based approach is proposed. This approach employs a multiplicative decomposition of the matrix of position-gradient vectors in the stress-free reference configuration into two position-gradient matrices. One matrix is associated with the reference-configuration geometry before the application of the thermal load, and the other accounts for the volumetric change due to the change in temperature. A numerical study demonstrated the implementation of the proposed gradient-based approach.

An analytical model is proposed to predict the stress–strain relationship of confined concrete subjected to reinforcement corrosion. The stress–strain graph of confined concrete with corroded reinforcement was predicted using estimation of four key parameters: maximum compressive stress, strain at maximum compressive stress, modulus of elasticity of concrete, and ultimate compressive strain of concrete. To validate the model, analytically predicted stress–strain curves of confined concrete of circular RC columns damaged due to corroded reinforcement were compared with those obtained from full-scale experimental tests with varying degrees of corrosion. The results of the comparison indicate good agreement. The RC columns had identical size, the same longitudinal steel reinforcement and spiral confinement type but with different spiral pitches providing varying levels of confinement. The corroded RC columns were categorized into four corrosion groups: noncorroded, low corrosion, high corrosion, and mechanical pitting corroded. The presented model is based on a modified version of the Mander’s universal model for RC columns.

Reinforced concrete (RC) structures are subjected to combinations of axial, shear, flexure, and torsional loading during an earthquake event. Comprehensive understanding of the behavior of shear panels is essential to predict the response of members under combined loading. This work focuses on the analytical modeling of RC shear panel elements. A baseline fixed strut-angle model (FSAM) was initially proposed for the shear behavior of RC panel elements, satisfying the three basic principles of mechanics: stress equilibrium, strain compatibility, and material constitutive behavior. The FSAM was later modified to consider the effect of dowel action and aggregate interlock through empirical relationships. Use of modified FSAM formulations for the estimation of the monotonic response of shear panels with different reinforcement ratios in longitudinal and transverse directions leads to loss of convergence after yielding of the transverse reinforcement. Thus, an accurate estimation of postyield response is not possible using the existing FSAM, which is critical for seismic design. This paper presents an improved algorithm for FSAM by employing experimentally validated constitutive relationships for the aggregate interlock mechanism. Comprehensive correlation studies considering parameters including the amount of reinforcement and concrete strength are reported to understand the improved FSAM. Predictions of the improved FSAM for shear panels with unequal reinforcement are better than those derived using the existing FSAM approach.

Due to the high in-plane stiffness and strength capacity of cross-laminated timber (CLT) panels, the mechanical behavior of CLT shear walls is mainly influenced by the mechanical performances of the connections. Several calculation models have been proposed considering the mechanical anchors effectiveness only along their primary direction. However, recent studies showed a relatively high stiffness and capacity of new typologies of angle brackets when subjected to uplift vertical loads, such as for the wall-to-floor Titan V (TTV) angle bracket, developed to obtain high mechanical performances along both the vertical-tensile and horizontal-shear direction. In this paper a study on CLT shear walls anchored with TTV angle bracket is presented. The aim of the work is to investigate the effects of the coupled shear-tension behavior of the connections at the wall level and the effectiveness of TTV as an alternative to traditional mechanical anchors. The paper presents results from full-scale experimental tests and finite-element (FE) numerical analyses in SAP2000, where an innovative macroelement has been developed to model the TTV coupled shear-tension behavior. The effects of the plastic load redistributions of the TTV angle bracket on the global mechanical behavior of the CLT shear wall are discussed.

A theoretical model is proposed to analyze the punching shear resistance in flat slabs of reinforced concrete in the presence of openings and stud-type shear reinforcement. Openings in flat slabs reduce resistance to punching. The magnitude of the loss of strength is influenced by the quantity, size, and position of the opening in the slab. The theoretical method presented in this work describes that once a load is applied onto the slab, a rotation occurs, giving rise to seven forces. These forces are related to the concrete and the flexural and shear reinforcement. The failure load is calculated by finding the solution of nonlinear equations developed from horizontal, vertical, and rotational balance of these forces. The failure criterion of these slabs with shear reinforcement was classified as internal or external to the shear reinforcement. The results showed theoretical breaking loads similar to those obtained experimentally, with a maximum variation of 7%.

Soil-structure interaction (SSI) effects are of interest for the seismic analysis and the design of tall buildings on shallow foundations, particularly when both the structure and soil undergo inelastic demands. The objective of this paper is to evaluate the interaction of nonlinear soil-structure systems using the direct fully-coupled approach for modeling SSI. Numerical simulations of linear and nonlinear tall buildings, combined with either fixed-base conditions at the ground level or an explicit soil domain, are performed. The soil domain was modeled assuming either linear elastic isotropic or multiple yield surface plane strain continuum constitutive models. An archetype 30-story building supported on a mat foundation was modeled using nonlinear link elements to control geometry, stiffness, and strength. Structural stiffness and mass profiles were algorithmically generated to satisfy prescribed modal characteristics of tall buildings and achieve a more realistic response. The influence of nonlinear material responses for both structure and supporting soils subjected to selected earthquake time histories is quantified using drifts, accelerations, displacements, hysteretic energy, and transfer functions. Nonlinear analyses considering SSI largely influenced the computed seismic structural response presented in this paper, showing a significant decrease of the seismic demands when compared to those demands obtained with linear SSI models, which impacts the structural behavior and has practical implications in seismic-resistant designs.

An experimental program was conducted to investigate the stress relaxation properties of large-diameter bars [65 to 70 mm (2.5 to 2.75 in.) nominal] for posttensioning applications. This study was a component of a large-scale research program to develop a more corrosion-resistant, posttensioning bar. The bars were fabricated from 4142 quenched and tempered (QT) carbon steel and three stainless steel alloys: Type 450, Type 630, and Type 2507. The experimental program objective was to evaluate the stress relaxation properties of these various materials. Stress relaxation losses were determined for 24 specimens by measuring the force change in the specimens for 1,000 h under constant strain. The influence of several additional parameters on relaxation was also evaluated including initial stress level, galvanization on plain (black) steel, coupled bars, and the variability provided by different steel heats. Measured losses are compared with established relaxation theory and relaxation limits provided in standard specifications. The results indicate relaxation losses are dependent on the type of stainless steel alloy and, for the alloys tested, can vary $\pm 50\%$ of the relaxation of plain carbon steel bars. Furthermore, different heats of steel can result in significant variation in the amount of relaxation. While standard design approaches can be used for stainless steel bars, material-specific data are necessary to ensure appropriate posttensioning forces are applied over the life of the structure.

Damping-ductility relationships, as applied in direct displacement-based design (DDBD), are products of equivalent linearization techniques used to estimate the nonlinear response of structures. Currently, suitable relationships are lacking for an increasingly wide range of flag-shaped hysteresis that is possible in practice. This paper seeks to fill that gap. Two commonly used numerical procedures are shown to be equivalent in terms of the equivalent viscous damping ratio (EVDR) produced. From approximately 1 million damping-ductility datapoints, an expression for the EVDR is proposed for flag-shapes defined by four parameters: the fundamental period, loading-to-initial stiffness ratio, unloading-to-loading stiffness ratio, and ductility. Compared to Jacobsen’s curves, the EVDRs obtained are more sensitive to the first two parameters, and this is reflected in the proposed expression. As Jacobsen’s EVDR assumes resonant conditions, the period-dependency is ignored and potentially underestimates the EVDRs for short periods (and vice-versa). A DDBD example demonstrates the design of a flag-shaped hysteresis using the proposed expression. The results of this study offer a flexible damping-ductility formula for the displacement-based design of self-centering seismically resilient structures.

A novel self-centering device that employs disc springs as its kernel components is developed and experimentally verified in this study. The device is suitable for use in self-centering braced frames and is expected to provide a large initial stiffness, reliable self-centering capability, and satisfactory energy dissipation. The fundamental mechanical behavior of the new device is described first. The component detailing, working principle, and fabrication process are discussed in detail. This is followed by a series of tests on individual disc springs and friction plates to gain an in-depth understanding of the performance of these basic components. Subsequently, a full-scale device designed based on a prototype building is physically tested, and the reliability of the specimen under multiple earthquakes is further understood by carrying out repeated rounds of cyclic loading. Among other findings, it is observed that the proposed device has excellent self-centering capability with equivalent viscous damping (EVD) of up to 36%. The device can provide sufficient deformability, corresponding to an available interstory drift of at least 4%. The device is capable of withstanding multiple rounds of loading with no degradation, highlighting its superiority for use against sequential strong earthquakes with no need to replace/repair. The analytical expressions are validated through comparisons against the test results, and a parametric study is then conducted to examine the effects of some key design factors on the device behavior. Based on the experimental and analytical studies, some practical design recommendations are finally given.

The seismic safety of acceleration-sensitive secondary elements rigidly connected to the primary structure can be ensured in the case of ordinary structures by simply and accurately estimating the largest peaks in the floor accelerations consistent with a given seismic hazard. A new modal combination rule is developed in this study to estimate the peak floor accelerations in the case of lumped mass, classically damped, multistoried structures. The formulation is based on stationary random vibration theory and the use of nonstationary peak factors together with the amplitudes of the specified design spectra. The proposed formulation is supported by the development of (1) an expression for estimating the peak factor for floor acceleration from the peak factors for modal displacement responses and peak modal contributions to the peak floor response, wherein both floor acceleration and modal peak factors are normalized by the (nonstationary) peak factor for input ground acceleration, and (2) a two-parameter power function for estimating the normalized modal peak factors for relative velocity from the oscillator period, together with the scaling equations for the two parameters in terms of ground-motion characteristics. A numerical study using five example buildings and six example ground motions shows that the proposed modal combination rule works well, with the absolute error averaged over all floors of the structure being less than 10% for 90% of the cases. Also, the proposed rule works better compared to when various peak factors are taken to be identical.

Ultrahigh-performance concrete (UHPC) has the potential to address seismic performance issues reported for rectangular hollow columns. However, an impediment to the use of UHPC is its limited flexural ductility compared with normal concrete (NC) with the same confinement. This study investigated UHPC rectangular, hollow cross-section bridge columns with HSS as a confinement alternative using flexure (moment-curvature), flexure-shear and finite-element analyses. The flexural analytical model, validated by tests in the literature, was used to perform parametric studies to assess the impact of HSS on column flexural ductility. Analysis results showed that HSS confinement can improve the flexural ductility of UHPC, making UHPC suitable for hollow columns. The flexure-shear interaction model considered the shear strength degradation with increasing displacements to estimate the failure mode. UHPC columns outperformed NC columns in delaying shear-controlled failure. Finite-element analysis was performed on columns with selected design parameters to understand the impact of UHPC on shear damage control. The ratio of flexure to shear displacements was higher in UHPC columns compared with NC columns due to UHPC’s higher shear resistance.

Bridge decks are the most stressed elements in a highway bridge due to direct loading from vehicular traffic and occasional overloading, combined with stresses induced by environmental effects and the use of deicing salts in cold wintery conditions. The use of structural aluminum alloys offers considerable promise for building modern bridges and for redecking aging and deficient bridges. Traffic barriers are mounted on bridge decks to provide a physical impassable limit to redirect errant vehicles safely onto the roadway. Current design standards require that the traffic barrier and anchorage system be physically tested under full-scale crash conditions to assure satisfactory interaction with impacting vehicles at the desired level of performance. Certain modifications to an already crash-tested and approved barrier may be permitted if it can be demonstrated by comprehensive analyses that they would not adversely affect the designed performance of the safety barrier. The present study seeks to develop and validate an anchorage design for attaching an already approved traffic barrier on bridge decks made from welded multivoid aluminum extrusions. The anchorage design facilitates installation and is able to absorb vehicular impact loads without compromising the structural integrity of the aluminum bridge deck. The study consists of two stages: (1) the capacity design and analysis of the attachment system based on equivalent static forces, and (2) a dynamic simulation of a full crash-test. This is followed by an approved procedure for verification and validation of the barrier-vehicle interaction, by comparing simulation results with observations from the original physical crash test.

Hollow structural sections (HSSs) are highly efficient in resisting compression, torsion, and bending. Their high torsional rigidity generally eliminates lateral-torsional buckling (LTB), which in turn eliminates the need for lateral bracing in flexural members. As a result, their plastic rotational capacity is mainly governed by flange local buckling (FLB) and web local buckling (WLB). Moment-resisting connections for single-HSS flexural members can be complicated. This study investigates the behavior of double-HSS flexural members under large displacement reversals. The study configuration consists of a double-HSS beam connected to a column through a center gusset plate secured by flare-bevel groove welds. The advantages of the proposed double-HSS moment connection are: (1) compared to a single-HSS, it effectively reduces the width-thickness ratios ($b/t$) of the flanges by using a double-HSS, thereby considerably increasing the member’s compactness and ductility; (2) it provides simple and practical connection details between the beam and column; and (3) it eliminates the need for lateral bracing. In addition, on-site welding can be eliminated by using shop-welded double-HSS beam-column stubs spliced by a bolted end connection. Experimental tests indicate that the proposed double-HSS moment connections showed a stable response up to a story drift angle of approximately 0.07 rad for the HSS sizes tested. Nonlinear finite-element analyses, including fracture behavior via the extended finite-element method (XFEM), were used to simulate test results, and finite-element analysis (FEA) was used to formulate the design procedure for the center gusset plate and welds connecting the double-HSS beam and column flange.

Despite having a high strength-to-weight ratio and being chemically inert, fiber-reinforced polymer (FRP) reinforcing bars are not currently used in reinforced concrete protective design due to their brittle nature and lack of ductility. This paper presents research on the innovative use of blended mixtures of FRP and steel rebar to activate self-centering behavior to return blast-loaded elements to their original position after the inertial loads are removed. Self-centering blast-resilient members promise reductions in residual damage, repair cost, and facility downtime after a terrorist bomb attack or accidental explosion. Large-scale reinforced concrete beams with different combinations of steel and glass FRP (GFRP) rebar were designed, constructed, and tested under progressively increasing blast loads generated by the Virginia Tech Shock Tube Research Facility. The results demonstrated that beams with hybrid reinforcing experienced reduced overall residual damage in comparison with similar conventionally reinforced concrete members. Increasing the self-centering ratio (SC) of beams, defined as the ratio of the restoring moment provided by the FRP to the resisting moment provided by energy dissipating steel rebar, increased the blast self-centering tendencies of the hybrid beams. Additionally, if the GFRP rebar ruptured during the blast, the presence of steel prevented a brittle failure mechanism and provided additional energy dissipation and redundancy. To encourage the use of hybrid FRP-steel reinforcement in blast-resistant construction, a series of protective design recommendations are made. Furthermore, a new response limit based on a blast self-centering index (BSI) is proposed to explicitly account for the residual damage state in the protective design process.

Recent full-scale testing of steel wide-flange columns under axial compression and cyclic lateral drifts for special moment frame applications showed that deep, slender columns could experience significant flexural strength degradation due to plastic hinge formation with buckling modes and considerable axial shortening within the hinge. Test results showed that the interaction between web and flange local buckling played a significant role for the observed degradation, even when the cross-sectional elements met the highly ductile limiting width-to-thickness ratios specified in the current seismic design standard for steel frames. These observations were also confirmed by numerical simulations. Enhanced limiting width-to-thickness ratios for the web of a wide-flange column for both special and intermediate steel moment frames are proposed to limit the severity of strength degradation and axial shortening.

Typical installations of seismic isolation assume flexurally rigid end conditions; however, in retrofit scenarios where bearings may be placed at the tops of columns or in bridges with tall piers, some rotation may occur at the boundaries. Very few experimental programs have explored the effects of these flexible boundary conditions; however, none have applied cyclic rotation at both top and bottom end plates in combination with cyclic horizontal demands, which is representative of potential loading with flexible boundary conditions. To address this gap, an experimental program on quarter-scale column-top mounted natural and lead-core rubber bearings was conducted. Rotations were applied at both the top and bottom bearing end-plates to investigate the impact of nonzero rotation boundary conditions on key design assumptions such as horizontal stiffness and rotational stiffness, and how these effects change with axial load beyond that for zero-rotation cases. Flexible boundary conditions reduce the horizontal stiffness, and the rotation-induced reduction in horizontal stiffness is dependent on the sum of the rotation at the ends, regardless of the rotation of one bearing end-plate with respect to the other. This rotation-induced decrease in stiffness is also dependent on axial load, with larger axial load leading to a higher dependency on rotation. Last, while it is known that the overlapping area method used for stability limits is conservative for rigid boundary conditions, this was shown to be true even for the bearing with a moderate shape factor ($S_1=19.6$) when supported by a flexible column. However, the overlapping area method was not conservative for the bearing tested with low shape factor ($S_1=7.9$), which exhibited a tangential stiffness of zero at an axial load less than the stability limit from this method.

An immeasurable amount of greenhouse gas emissions during the process of steel purification and concrete production has attracted environmentally friendly engineers’ attention to extend and enhance the use of wood as a structural material. During the last two decades, cross-laminated timber (CLT) has emerged as a high-strength engineered wood product to improve resistance and performance of timber structures, and is being used as a replacement for some mid and low-rise commercial buildings made of concrete and steel in the US. Due to the fact that CLT is a relatively new engineered wood product, there is a lack of knowledge on the mechanical behavior of CLT members and connections. The goal of the present study is to characterize the mechanical properties (specifically shear resistance) of three common types of CLT diaphragm connections including surface spline, half lap, and butt joint, and estimate the behavior of those connections in ultimate limit states, such as earthquake loads, and also serviceability limit states. In doing so, an experimental schedule was developed for a total of 56 tests accounting for different test variables including fastener orientation, type, length, and spacing. More specifically, two types of dowel-type fasteners, namely nail and screw, were considered, while the effect of fastener spacing and inclination was considered by changing the spacing of nails and driven angle of screws. The exerted force and displacement were recorded generating hysteresis curves to assess the failure mechanisms, shear modulus of elasticity, ultimate allowable shear strength and displacement, and energy dissipation of the various connections studied. A finite-element model based on elastoplastic behavior of CLT for a half-lap connection was also developed to estimate the shear behavior of this type of connection numerically and compare it with the experimental findings. Finally, the experimental results were used to compute the optimized hysteretic parameters (and their statistics) for the CUREE-SAWS hysteretic model for further adoption in modeling of diaphragm components by practicing engineers and researchers.

This paper introduces a grid-purlin system, which was composed of secondary rectangular-hollow-section grids welded onto the top flange of I-shaped beams of moment frames. The welded grid-purlin itself may play a role of a lateral bracing member for the welded beam. However, the ultimate strength, plastic rotation capacity, or other structural characteristics of this grid-purlin system remain poorly understood. This paper presents two full-scale cyclic loading tests on specimens with I-shaped beams 700 mm deep, 240 mm wide, and 13 m long. The diagonal length of grids in the square grid-purlin of the specimen was 1.3 m on-center, and two different depths of the sections were selected for the purlin sections. Both specimens successfully achieved fully plastic moments at a plastic rotation exceeding 0.04 rad. This shows that the grid-purlin system provides reliable lateral bracing. Continuum finite-element (CFE) analysis was performed to simulate the hysteretic experimental response of the grid-purlin system. This CFE model was used to examine the plastic rotation capacity for a variety of combinations of I-shaped beams and grid-purlins.

Shake-table studies were conducted on a large-scale, two-span accelerated bridge construction (ABC) bridge model that incorporated 38 precast concrete elements and six emulative ABC connection types. The studies were aimed to assess the seismic performance of the bridge model and the six ABC connections under biaxial horizontal ground motions simulated at the Earthquake Engineering Laboratory at the University of Nevada, Reno. The bridge model was subjected to successive earthquake motions ranging from 20% to 200% of the design earthquake motion. Test results showed that the ABC bridge model matched the target performance of cast-in-place (CIP) bridges by limiting plastic hinging to columns and maintaining other components as damage-free. The ABC connections maintained the structural integrity of the system even under drift ratio demands on the columns higher than 7.5% combined with substantial in-plane rotation (e.g., larger than 0.008 rad) of the superstructure.

This paper proposes an innovative thin-walled square concrete-filled steel tubular (CFST) column with a circular/octagonal steel lining tube, in which the outer steel tube and the lining tube are fabricated independently of each other and then connected by slot welds. The advantages of a simplified manufacturing process, an insensitivity to local buckling, and good confinement could be expected in this composite column. Twelve short columns were tested to failure under compression, and various key parameters including nominal width-to-thickness ratios of steel tubes, stiffener types, yield strengths of steel tubes, and lining tubes were considered. The test results indicated that the proposed steel lining tubes were able to improve the axial behavior of these thin-walled square CFST short columns in various ways, including a more uniformly spaced buckling pattern with smaller intervals, larger axial stiffness, higher section resistances, and enhanced confinement and ductility. The octagonal lining tubes were more effective than the circular ones in terms of buckling constraints while the circular lining tubes were superior in terms of confining enhancement. A finite-element parametric analysis was also carried out to assess the axial resistances of these thin-walled square CFST columns with lining tubes. A simplified model was developed incorporating both the postlocal buckling of the square steel tubes and the confinement of the lining tubes.

A set of acceleration records obtained at specific points of an actual reinforced concrete, four-story building structure subjected to forced vibrations are presented and documented in this data paper. The structure has vertical setbacks, which gives it natural eccentricity along one direction. The tests were conducted to study the torsional behavior of the structure subjected to forced and ambient vibrations. A mechanical eccentric-mass exciter was used for the tests. The exciter was attached to the roof slab at two locations, and the resultant force was varied in position, magnitude, direction, and frequency. During the tests, the only vertical loads applied to the building structure were those resulting from the self-weight of the columns, beams, and slabs. No additional vertical dead or live loads existed. Given the characteristics of the structure and the tests, the generated data can be used for several purposes, such as building torsion and structural identification, among others. The simplicity of the building allows for the faithful analytical replication of the conducted tests because there is no interference with nonstructural elements or live loads.

This study summarizes the moisture content (MC) monitoring results of two nail-laminated timber (NLT) bridge decks in New Brunswick, Canada. The MC monitoring systems were installed in the NLT decks of two newly built bridges, Clark Mill Pond and Shikatehawk No. 5, in New Brunswick, recording the MC through the electrical resistance (ER) method. The calibration test was conducted to correlate the ER values ($\mathrm{\Omega }$) and MC values (%). It was found that the MC values varied from 9.9% to 18.2% and 12.8% to 19.7% for Clark Mill Pond Bridge over 239 days and Shikatehawk No. 5 Bidge over 189 days, respectively. Based upon these MC monitoring data, the NLT deck surfaces could likely not be prone to rotting caused by biotic attack during the monitoring period.

A comprehensive experimental database of bare steel and composite flush end-plate (FEP) connections, covering tests conducted within the last 50 years, was collated and made public. The database includes deduced and tabulated parameters defining the configuration, geometric and material properties, and observed deformation and failure modes for more than 360 test specimens. The database also includes the specimens’ monotonic/cyclic responses in the form of digital moment versus rotation data. The database will aid researchers and engineers in benchmarking empirical, mechanical, or continuum finite-element models; assessing the robustness of existing numerical modeling and designing methodologies for end-plate connections; and developing new predictive models or damage fragility functions. The database also serves as an exemplar for the systematic development of similar databases for other types of semirigid connections. A graphical interface was developed to aid users in exploring, filtering, and assessing the database.

This paper presents results from the dynamic monitoring of a reinforced concrete school building located in Camerino (central Italy) during the seismic swarm following the first main shock of the Central Italy earthquake that occurred in August 2016. After the main shock of August 24th, ambient vibration tests were executed on the building to identify its modal dynamic behavior, which was assumed as benchmark to study changes in the structural response because of the subsequent events. A three-day dynamic monitoring was then performed with the aim of investigating changes in the dynamic behavior of the building subjected to ambient and seismic excitations. A procedure to identify the nonlinear response of the structure subjected to seismic events is presented, starting from an optimization methodology that permits the identification of the structure dynamics within time windows in which the building dynamic behavior can be considered linear time-invariant. Data show the variability of the modal properties, resonance frequencies, and damping ratios of the building, with the earthquake intensity.